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This is a genuine, Swiss‑made ETA 7750-8080 clutch for the 60‑seconds chronograph hand. It serves as the engaging gear that connects and disconnects the chronograph seconds wheel from the drive train, thereby initiating and halting the central 60‑seconds chronograph hand.
Genuine Quality: Factory‑produced by ETA Switzerland, brand new, with materials and precision fully compliant with the original movement’s design specifications.
Compatible Movements: ETA/Valjoux 7750, 7751, 7753, 7754 and most 7750‑derived calibers. The 7750 movement, introduced in 1974， has become the most widely used automatic chronograph in watchmaking history.
Part Number: 7750-8080 / ETA 7750.8080.
Core Function: The clutch assembly is the central engagement mechanism that connects and disconnects the chronograph seconds wheel from the drive train. The assembly consists of the outer clutch wheel and an inner clutch spring. When the chronograph is started, the spring pushes the gear into the engaged position, and releases it to instantly brake the hand when stopped.
Dual-Function Design: The designation “Clutch / 60 S” directly indicates its role in the 60‑seconds chronograph circuit. A specially profiled spring performs the dual role of engagement and braking of the central seconds hand.
Repair Value: If the central seconds hand hesitates, stutters, or fails to start (or drifts when it should be stopped), the clutch assembly is one of the first components to inspect and replace.
⚠️ Single‑use component: The clutch is a high‑stress component in the chronograph module. Once removed or exhibiting function loss, it must be replaced with a new part and cannot be reused.
⚠️ Inspect mating parts: When replacing the clutch, also inspect the chronograph seconds wheel and its pivots for wear; replace them as a set if necessary.
⚠️ Lubrication restriction: Apply a microscopic amount of Moebius 9010 only to the clutch’s pivot bearing surface. The gear teeth and the spring contact area must remain completely dry – excess oil will cause the seconds hand to drift or fail to lock when reset.
⚊ Water resistance: This part replacement does not directly affect water resistance, but since the case must be opened, reassembly requires a pressure test (3‑5 bar) to verify the seals.
Q1: What are the most common failures of the ETA 7750-8080 clutch?
A: The most frequent failure is fatigue of the tiny internal spring, which causes a sluggish start or drifting stop of the central second hand. Wear on the braking surface can also lead to reset instability.
Q2: How can I distinguish a genuine ETA part from a counterfeit?
A: Genuine ETA parts have characteristic surface finishing and machining precision. Counterfeit parts often use springs with different hardness or elasticity, affecting the tactile feel. Always purchase from trusted suppliers.
Q3: After replacing the clutch, the chronograph works but the central seconds hand still wobbles slightly. Why?
A: The seconds hand itself could be slightly bent, or the chronograph seconds wheel might have poor concentricity. Check the hand for straightness and inspect the wheel for axial run‑out. Consider replacing the wheel if it is damaged.
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